Isolation and purification of various phospholipid exchanged proteins will continue. The proteins will be used to study the distribution of phospholipids between inside and outside layers of membranes in red blood cells and in rat liver microsomes. The kinetics of formation of chylomicron remnants in cholesterol-fed rabbits will be studied. We will attempt to estimate the relative contribution of liver and intestine to cholesterol-rich lipoproteins in rabbit plasma. BIBLIOGRAPHIC REFERENCES: Catalytic properties of phospholipid exchange protein from bovine heart. L. W. Johnson and D. B. Zilversmit. Biochim. Biophys. Acta 375:165-175 (1975). Use of phospholipid exchange protein to measure inside-outside transposition in phosphatidylcholine liposomes. Biochim. Biophys. Acta 375:176-185 (1975).